1. Field of the Invention
The present invention generally relates to medical devices and surgical procedures for correcting tissue defects, and more specifically relates to applicator instruments having end caps that facilitate the accurate placement of surgical fasteners for the fixation of mesh implants during open repair procedures.
2. Description of the Related Art
Hernia is a condition whereby a small loop of bowel or intestine protrudes through a weak place or defect within the abdominal muscle wall or groin of a patient. This condition commonly occurs in humans, particularly males. Hernias of this type may result from a congenital defect, or may be caused by straining or lifting heavy objects. Lifting heavy objects can generate a large amount of stress upon the abdominal wall, which may rupture or tear to create the defect or opening. In any case, the patient may be left with an unsightly bulge of abdominal contents protruding through the defect, which may result in pain, reduced lifting abilities, and in some cases, impaction of the bowel, or possibly other complications if the flow of blood is cut off to the protruding tissue.
A common solution to the above-described problem may be surgery. During an open surgical procedure, the defect is accessed and carefully examined through an open incision. Careful examination is required due to the network of vessels and nerves which exist in the area of a typical defect, which requires a surgeon to conduct a hernia repair with great skill and caution. Within this area can be found vascular structures such as gastric vessels, the external iliac vessels, and the inferior epigastric vessels.
Once the surgeon is familiar with the anatomy of a patient, the surgeon carefully places the viscera back into the patient's abdomen through the defect. Repairing the defect can involve closure of the defect with sutures or fasteners but generally involves placing a surgical prosthetic such as a mesh patch over the open defect, and attaching the mesh patch to the abdominal wall or inguinal floor with conventional suture or with surgical fasteners. The mesh patch acts as a barrier and prevents expulsion of bowel through the defect.
At present, there are a variety of surgical instruments and fasteners available for attaching a mesh patch to tissue. One type of instrument is a surgical stapler whereby a stack of unformed staples are contained within a cartridge in a serial fashion sequentially advanced within the instrument by a spring mechanism. A secondary feeding mechanism separates a distal-most staple from the stack, holds back the remainder of the stack, and feeds the distal-most staple into a staple forming mechanism. Feeding mechanisms of this type are found in U.S. Pat. No. 5,470,010 to Rothfuss et al., and in U.S. Pat. No. 5,582,616, also to Rothfuss et al.
Another hernia mesh attachment instrument uses a helical wire fastener that resembles a small section of spring. Multiple helical wire fasteners may be stored serially within a 5 mm shaft, and may be corkscrewed or rotated into tissue. A load spring may be used to bias or feed the plurality of helical fasteners distally within the shaft. A protrusion extends into the shaft to possibly prevent the ejection of the stack of fasteners by the load spring and may permit passage of a rotating fastener. Instruments and fasteners of these types are found in U.S. Pat. No. 5,582,616 to Bolduc et al., U.S. Pat. No. 5,810,882 to Bolduc et al., and in U.S. Pat. No. 5,830,221 to Stein et al.
The above-listed references teach using a spring mechanism to feed a plurality of fasteners through the surgical instrument. Spring mechanisms typically use a long soft coil spring to push a stack of fasteners through a guide or track within the shaft of the surgical instrument. These types of feeding mechanisms may be generally simple and reliable, however, they require a supplemental valving mechanism to separate and feed the lead surgical fastener from the stack.
Other instruments dispense surgical fasteners using either a reloadable single shot instrument or a rotary magazine that holds a small number of fasteners. These types of surgical fastening instruments can be found in U.S. Pat. Nos. 5,203,864 and 5,290,297, both to Edward Phillips. These instruments have not gained acceptance by the surgical community, possibly due to their single shot capabilities and the large size of the rotary magazine, which can restrict the use of such an instrument to an open procedure.
An instrument with a reciprocating feeding mechanism is described in U.S. Pat. Nos. 5,601,573; 5,833,700; and 5,921,997 to Fogelberg et al. The Fogelberg et al. references teach a clip applier with a feeding mechanism that utilizes a reciprocating feed bar to feed a serial stack of clips. A feeder shoe may operably engage with and move with the distally moving feed bar and may slidingly engage with the proximally moving feed bar. Thus, the feeder shoe may index or push the stack of clips distally with the distally moving feed bar and remains stationary relative to the proximally moving feed bar. A supplemental valving mechanism separates the distal-most clip from the stack and holds the remainder of the stack stationary as the distal-most clip is applied onto a vessel. Although the Fogelberg et al. references teach a reciprocating feeding mechanism with a single reciprocating member, they do not teach the use of the clip applier in the attachment of hernia mesh, nor do they teach the individual driving or feeding of each clip by a moving member.
Another fastener feeding mechanism that uses reciprocation is that disclosed in U.S. Pat. No. 4,325,376 to Klieman et al. A clip applier that stores a plurality of clips in a serial fashion within a clip magazine is disclosed. The clips are in a stack wherein the proximal most clip may be pushed or fed distally by a pawl that may be ratcheted or indexed distally by a reciprocating member or ratchet blade with each actuation of the instrument. As the pawl indexes distally, it can push the stack of clips distally. A secondary valving mechanism may be also described. Thus, the feeding mechanism of Klieman et al. teaches the use of a single reciprocating member and pawl to push or feed the stack of clips distally, and may require a secondary valving mechanism to feed the distal most clip.
U.S. Pat. No. 3,740,994 to DeCarlo Jr. describes a novel reciprocating feeding mechanism that may index a plurality of staples or clips, and may ready them for discharge by reciprocating one of a pair of opposing leaf spring assemblies. The staples reside serially within a guide rail with a fixed leaf spring assembly extending into the plane of the guide rail. A reciprocating leaf spring assembly may oppose and extend inwardly toward the fixed leaf spring assembly. As the reciprocating leaf spring assembly moves distally, each of individual leaf springs of the assembly may engage a staple and move it distally. The distally moving staples deflect the local individual leaf springs of the fixed leaf spring assembly, and the deflected leaf springs may return to the un-deflected position after passage of the staple. As the moving leaf spring assembly moves proximally, the leaf springs of the fixed leaf spring assembly hold the staples stationary and prevent proximal movement thereof. A secondary guide rail and valving mechanism may be provided to separate a single staple from the stack for forming and can hold the stack of staples stationary as the single clip is formed.
Additionally, similar feeding mechanisms are disclosed in U.S. Pat. No. 4,478,220 to DiGiovanni et al. and U.S. Pat. No. 4,471,780 to Menges et al. Both of these related patents teach a reciprocating feeding mechanism that uses one fixed member and one reciprocating member to feed or index a plurality of clips distally. Angled flexible fingers may be hingedly attached to the reciprocating member and operatively engage the clips when moving distally, and slidingly engage with the clips when moving proximally. The angled flexible fingers within the fixed member deflect out of the way when the clips move distally and spring up to stop proximal movement of the clip after the clip has passed. A secondary valving mechanism is also disclosed.
Commonly assigned U.S. Patent Application Publication No. 2002/0068947, the disclosure of which is hereby incorporated by reference herein, teaches a device for delivering a plurality of individual surgical fasteners. In one embodiment, the delivery device includes a drive mechanism having distal and proximal ends. The drive mechanism has a moving member and a fixed opposing member, whereby the moving member is moveable proximally and distally with respect to the delivery device. The moving member has a sharpened distal end for piercing tissue. The device includes at least one surgical fastener located between the first and the second members. Each of the surgical fasteners has a proximal end and a distal end. The device also has an actuator having at least two sequential positions. A first position for advancing the moving member distally and piercing tissue, and a second position for retracting the moving member proximally, thereby deploying the distal end of the fastener.
Tacks for mesh fixation have generally been made of metal, such as stainless steel, nitinol, or titanium. The metal tacks were necessary to provide for sufficient holding strength, penetration of various prosthetic meshes, and for ease of manufacture. Until recently, there were no absorbable tacks available on the market, and surgeons could only use absorbable sutures in order to provide a fixation means that did not permanently stay in the body. However, using sutures is exceedingly difficult for some repair procedures. With surgical trends leading to minimum foreign body accumulation, an absorbable tack with minimum profile is needed.
In spite of the above advances, there remains a need for further improvements. In particular, there remains a need for applicator instruments that enable surgeons to accurately and easily dispense surgical fasteners into tissue for tissue repair procedures, there remains a need for applicator instruments that enable surgical fasteners to be accurately and easily dispensed in small areas, and for surgical fasteners that are absorbable.